Importance Of Sleep For Muscle Retention

We know the importance of sleep when it comes to recovery, but did you know it also plays a role in body composition?

A common thing I hear amongst clients is that ‘they get enough sleep for them.’ Further questioning then indicates that this could look like 6 hours on average per night. Time and time again research has shown that humans need between 7-9 hours on average, with athletes requiring up to 9 due to the physical demands placed on their bodies.

Now, put someone in a calorie deficit who is low on sleep and it’s a sure recipe for disaster. When we’re low on sleep, we experience an increase in the hormone ghrelin and a reduction in leptin. Ghrelin is a hormone that is released from the stomach and signals to the brain that it’s time to eat. Leptin is produced by the body’s fat cells and regulates hunger through signalling to the brain that we’re satisfied/full. With a decrease in sleep comes a decrease in leptin and overall energy and an increase in hunger, making us more likely to move less and eat more which is counterintuitive to fat loss if we’re trying to be in an energy deficit.

This is where it gets interesting..a study explored sleep status and fat loss by comparing middle aged overweight populations and putting them both in equivalent calorie deficits. Over two weeks, one group slept for 5.5 hours per night and the other 8.5 hours per night.

Interestingly, the group that slept for 8+ hours per night experienced higher rates of muscle retention (and increased fat loss) when compared to the 5.5 hour cohort who lost 55% less fat and experienced a 60% increase in lean body mass loss. For a strength/power athlete looking to maximise muscle retention in a calorie deficit, this is not ideal!

It was predicted that the cohort sleeping 5.5 hours per night were in a ~500kcal deficit daily while the 8.5 hour cohort were in a 900kcal deficit, despite being in equivalent calorie deficits.

Findings indicate the overall importance of sleep in humans when maintaining fat free body mass during an energy deficit and support current research indicating compromised sleep can contribute to difficulty adhering to calorie restriction due to the endocrine system’s response.

In short: science says sleep contributes to the maintenance of fat free body mass during an energy deficit and can have a negative influence over positive dietary interventions when pursuing fat loss.


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